Textile machine control system



NOV. 24, 1970 w, G H

TEXTILE MACHINE CONTROL SYSTEM 4 Sheets-Sheet 1 Filed July24, 1968 WIIIIIIA IIII 'IIIIIII M/VEN/OR Nov. 24; 1970 W. 61TH 3,543,100

TEXTILE MACHINE CONTROL SYSTEM Filed July 24; 1968 4 Sheets-Sheet 2 FIG.2 l3

FIG.4

Nov. 1970 w. GITH v 3,543,100

TEXTILE MACHINE CONTROL SYSTEM Filed July 24, 1968 4 Sheets-Sheet 5 FIGS Nov. 24; 1910- w. GITH 3,543,100

Ii TEXTILE MACHINE CONTROL SYSTEM Fil e d July 24,, 1968 4 Sheets-Sheet I United States Patent 3,543,100 TEXTILE MACHINE CONTROL SYSTEM Walter Gith, Monchen-Gladbach, Germany, assignor to Walter Reiners, Monchen-Gladbach, Germany Filed July 24, 1968, Ser. No. 747,263 Claims priority, applicatigrl (figrmany, July 27, 1967,

R Int. Cl. D04: 3/38 US. Cl. 317-130 4 Claims ABSTRACT OF THE DISCLOSURE DESCRIPTION OF THE INVENTION The present invention relates to a textile machine control system. More particularly, the invention relates to a textile machine control system which includes a switching amplifier for electronic yarn or thread regulation and wherein the alternating voltages produced by the travelling yarn are rectified and then charge a storage capacitor which controls a stop control member of the textile machine.

It is known, as described in United States Patent No. 3,043,991, in connection with electronic yarn regulation in textile machines, to use the alternating voltages, produced by the travelling yarn in a photosensitive device or member, to charge a storage capacitor after amplification and rectification, and to utilize the capacitor to control the stop control member of the textile machine. As soon as the yarn travel is interrupted, due, for example, to a tear in the yarn, or due to a separation when starting a yarn cleaner, or due to an idle starting winding, no alternating voltages are produced. The storage capacitor is discharged, thereby releasing the stop control member, so that the drive of the textile machine is interrupted. It is also known to use other contact-free circuit or switching components or members such as, for example, the dielectric constant of a capacitor, to control the yarn in a textile machine, or to utilize so-called electromechanical sensing components or members which are actuated by yarn passing over them. The system of the present invention may be utilized for all types of electronic yarn regulation which produces alternating voltages in dependence upon the yarn travel.

The storage capacitor for the control of the stop control member of the textile machine functions to store a pulsating direct voltage, after rectification of the alternating voltage, so that the stop control member is not actuated, under any circumstances, for as long as the yarn travels. The capacitance of the storage capacitor and the magnitude of the discharge resistance must be so dimensioned, therefore, that the capacitor charge cannot fall below the predetermined stop control minimum, even during decrease in voltage.

On the other hand, if there is an interruption of the yarn travel, that is, when the alternating voltage produced by the yarn travel is interrupted or ceases, the storage capacitor should discharge as soon as possible in order to stop the drive of the textile machine. Since the time constant of the capacitor and of the discharge resistance should be as small as possible, it is obvious that the two aforementioned requirements are in conflict.

The principal object of the present invention is to provide a new and improved textile machine control system.

An object of the present invention is to provide a textile machine control system for electronic yarn regulation which provides extremely short stopping intervals when the yarn travel is interrupted, despite the aforementioned conflicting requirements.

In accordance with the present invention, the solution to the problem lies in connecting in series with the storage capacitor, a full-wave rectifier, as well as a circuit, for raising the amplitudes of the high frequencies and lowering the amplitudes of the low frequencies. Furthermore, at least the last amplifying stage is so dimensioned that small voltage amplitudes may lead to overloading.

Known types of textile machine control systems for electronic yarn regulation utilize those alternating currents, produced by the yarn travel, which result from the cross-sectional changes which lie below the magnitude which is to be picked up by the yarn cleaner. However, these cross-sectional changes are rarely sudden, but usually proceed very gradually, so that the alternating voltages they produce have only relatively low frequencies. This entails, however, large capacitances and long stopping intervals.

The present invention is based upon my recognition that the disadvantages of the known systems may be avoided by utilizing higher frequencies, if higher frequencies are utilized. In addition to the alternating voltages resulting from the cross-sectional changes of the yarn, other alternating voltages occur due to oscillations of the yarn and oscillations resulting from the surface quality or roughness of the yarn, as well as resonance oscillations of the electromechanical devices released by the aforementioned oscillations. Due to the yarn travel, the various oscillations produce a frequency spectrum for the alternating voltages, which in part has very high frequencies. Especially high alternating voltage frequencies are produced, thereby, by the yarn roughness if, for example, a photosensitive yarn regulating member is made so narrow, in the direction of the yarn travel, that the individual fibers extending from the yarn cause voltage fluctuations. The solution of the present invention for this problem utilizes my recognition and simultaneously utilizes the following three features.

(1) By connecting the storage capacitor in series with a full-wave rectifier, both half-waves of the alternating voltage produced by the travelling yarn are utilized for charging the capacitor, so that the capacitance of the capacitor may be considerably reduced thereby reducing the time constant of the RC storage member.

(2) Through the circuit for raising the amplitudes of high frequencies and lowering the amplitudes of low frequencies, the rapid oscillations contained in the frequency spectrum of the alternating voltages, caused by the travelling yarn, are utilized, so that the capacitance may be further reduced.

(3) By so dimensioning at least the last amplifier stage so that even small voltage amplitudes may lead to overloading, the discharge time constant of the RC storage member may again be considerably reduced.

The combination of the foregoing three features leads to the surprising result of a very considerably shortened stopping interval. The stopping interval is shortened by as much as 96%. The shortest stopping interval of the known systems is approximately 50 milliseconds, whereas the stopping interval of the system of the present inlvention is 2 milliseconds or less.

Bandpass filters, or the like, may be utilized to raise the amplitudes of the high frequencies and to lower the amplitudes of the low frequencies. A particularly simple construction of the textile machine control system or switching amplifier of the present invention is provided if, in accordance with the invention, two output potentials of an amplifying stage whose respective polarities are in phase opposition with a predetermined reference potential, are connected to the series connection of a reactive impedance and an active impedance. The electrical center of the series connection is connected to the input of an amplifier stage in a manner whereby a positive feedback is provided for the high frequencies and a negative feedback is provided for the low frequencies.

In accordance with the present invention, a textile machine control system comprises a stop control member. A transducer produces alternating voltages in response to changes of yarn travel conditions in the machine. A frequency-responsive circuit connected to said transducer raises the amplitudes of high frequencies and lowers the amplitudes of low frequencies. A rectifier circuit connects a capacitor to the frequency-responsive circuit for changing the charge of the capacitor in response to changes in frequency-responsive amplitude. An amplifier connects the capacitor to the stop control m mber whereby the system is controlled for rapid stopping performance in response to small voltage changes of the transducer.

The textile machine control system comprises switching amplifier network having several cascade-connected stages of which at least one constitutes the aforementioned amplifier. The rectifier circuit is a full-wave rectifier network and is connected between the one stage and a preceding stage of the amplifier network. One of the amplifier stages has two output points whose respective output potentials have a phase opposed to that of a given reference potential. The frequency-responsive circuit comprises a series connection of a reactive impedance and an active impedance extending between the two points and having an electrical midpoint connected to the input of a preceding stage of the cascade network so as to form a positive feedback for high frequencies and a negative feedback for low frequencies.

The amplifier network comprises a transistor amplifier in each of said cascade stages. One stage is the output stage of the network, the two output points being connected 'with the emitter and the collector respectively of the transistor in the next-preceding stage of the network. The full-wave rectifier and capacitor are connected in series between the two output points.

In order that the present invention may be readily carried into effect, it will now be described with reference to the accompanying drawings, wherein:

FIG. 1 is a circuit diagram of an embodiment of the textile machine control system of the present invention;

FIGS. 2 to 4 are vector diagrams explaining the operation of the embodiment of FIG. 1;

FIG. 5 is a graphical presentation of the voltage to aid in illustrating the operation of the embodiment of FIG. 1; and

FIG. 6 is a circuit diagram of a modification of the embodiment of FIG. 1.

In the figures, the same components are identified by the same reference numerals.

In FIG. 1, an optical transducer 1 operates without contacts to produce alternating voltages in accordance with travelling yarn Y. The photoelectric or optical transducer 1 comprises a very narrow photosensitive component or element F with a slitted or slotted diaphragm B positioned adjacent the photosensitive component on side of a light source L in a manner whereby even the individual fibers, extending or standing away from the yarn produce voltage fluctuations or variations in the circuit of the photosensitive element F. The light source L produces a light beam R which is directed to the yarn Y and thence through the diaphragm B to the photosensitive element F. Furthermore, high alternating voltage frequencies may be produced as a result of positioning yarn guide members or rollers G1 and G2 of the 'winding machine closely adjacent the optical transducer 1 at the surface of the diaphragm B facing the light source L. Thus, very rapid yarn oscillations occur in the vicinity of the transducer 1.

A capacitor 2 is connected in parallel with the photoelectric transducer 1 and is so dimensioned that it-shortcircuits high-frequency interference voltages, thereby blocking them from the stopping amplifier. A capacitor 3 is connected in series with the photoelectric transducer 1 and functions to permit only the alternating voltages of said photoelectric transducer to be delivered to the amplifier.

The alternating voltage amplifier has three stages. A first transistor 7 is directl connected to the capacitor 3. A second transistor 8 is directly connected to the first transistor 7. A third transistor 9 is directly connected to the second transistor 8. A potentiometer 6, a capacitor 4 and a resistor 5 provide the amplifier with automatic working point regulations. The input resistance of the transistor 7 is so increased by an emitter resistor 20, that the photosensitive element works almost at no-load voltage. This makes the input alternating voltage largely independent, in a known manner of the illumination provided by the light source L.

The alternating voltages of the photoelectric transducer 1 are amplified in the alternating voltage amplifier by the transistors 7, 8 and 9. The amplified alternating voltages are utilized to charge a capacitor 22, which controls the stop control member of the textile machine, via a direct voltage amplifier comprising a fourth transistor 24. If the textile machine to be controlled has several electronic yarn regulators such as, for example, a multiple spooling machine, a cutting machine, or the like, several direct voltage terminal amplifiers may be connected with the circuit output terminal 27 via a common diode network 26. The stop control member of the textile machine may be connected between the circuit output terminal 27 and the negative pole 32 of a source of voltage supply. Thus, for example, a power amplifier 41 of known type may be connected between the output terminal 27 and the negative pole 32 of the source of voltage supply and a stop control magnet 42 may be connected to the output of said power amplifier.

A full-wave rectifier 21 charges the storage capacitor 22, so that said capacitor is charged with both half-waves of the amplified alternating voltage. The full-wave rectifier 21 is connected to the last stage of the alternating voltage amplifier. That is, the full-wave rectifier 21 is connected to two output potentials whose polarity is in phase oppositron relative to a predetermined reference potential. In the embodiment of FIG. 1, these output potentials are provided at the points 10 and 11, since the transistor stage 9 is a known phase inverter stage. The voltage drops at the resistors 91 and 92 are in phase opposition, as hereinafter described.

When the transistor 9 is in its non-conductive condition, the full positive potential of the supply or operating voltage applied to the points 31 and 32 appears at the point 10 and the full negative potential appears at the point 11. If the resistors 91 and 92 in the collector and emitter circuit of the transistor 9 are equal in resistance value, a gradual switching of the transistor 9 to its conductive condition will cause the potential of the point 10 to drop in the direction of the negative potential of the point 32, while the potential of the point 11 will rise in the direction of the positive potential of the point 31, until both said points will have the same voltage when the transistor 9 is in its fully conductive condition. At a gradual switching of the transistor 9 to its non-conductive condition, the potentials of both points 10 and 11 vary in the exact opposite sense and thereby return to their original values. The output potentials at the points 10 and 11 of the amplifier stage 9 are thus in phase opposition, with regard to their polarity, relative to a predetermined reference potential. The reference potential may be selected by a selection of the resistance values of the resistors 91 and 92. As previously mentioned, the working point of the transistor stage 9 is adjusted, during its inactive period, via the potentiometer 6 at half-control, as in all alternating voltage amplifiers. The alternating voltage of the output potentials at the points 10 and 11 is then supplied to the full-wave rectifier 21, via capacitors 18 and 19, which separate the proportion of direct current.

As hereinbefore described, the connection of the fullwave rectifier 21 to the storage capacitor 22 provides the advantage that said storage capacitor is charged with both half-waves of the alternating voltage, so that said storage capacitor, the coupling capacitors 18 and 1'9, the collector resistor 91 and the emitter resistor 92 of transistor 9, as well as the base protecting and discharge resistor 23 of the direct voltage amplifier transistor 24 may be reduced. Since these RC members determine the charge and discharge periods of the capacitor 22, this feature alone results in a considerable reduction of the stopping interval.

In accordance with another feature of the present invention, the amplitude of high frequencies is raised and the amplitude of low frequencies is lowered. In the preferred embodiment of FIG. 1, the two aforementioned output potentials, whose polarity is in phase opposition relative to a predetermined reference potential, at the points 10 and 11 of the amplifying stage 9, are connected to the series connection of a reactive impedance 14 and an active or resistive impedance 15. The electrical center 13 of said series connection 14, is thereby connected to the input 12 of the amplifying stage 8, via a capacitor 16 and a potentiometer 17, as shown in FIG. 1.

The positive feedback of the high frequencies and the negative feedback of the low frequencies is provided in the following manner. The active impedance 15 comprises a purely ohmic resistance and the reactive impedance 14 comprises a capacitive reactance. The magnitude of the reactive impedance 14 and of the active impedance 15 are so selected or determined that for the average transmitting frequency of the amplifier, the magnitude of the reactive and active impedances is equal, that is The voltage drop U at the active impedance 15 is then equal to the voltage drop U at the reactive impedance 14. Since U and U are equal and are of opposite phase, a voltage U results at the points 12 and 13. In unloaded condition, the voltage U has a phase angle =90 relative to the voltage U between the points 10 and 11. This is clearly shown in the electrical vector diagram of FIG. 2. The reference numerals of the points of the vector diagram of FIG. 2 are the same as those of FIG. 1 An additional phase rotation via the capacitor 16 and the potentiometer 17 remains within a negligible range if said capacitor 16, which functions only to block the direct voltage from the base of the transistor 8, has a much larger capacitance than the capacitor 14, and also if the potentiometer 17 has a very high ohmic resistance.

Although, as shown in the vector diagram of FIG. 2, the positive and the negative feedback cancel each other out due to the equal magnitudes of the voltage drops at the impedances 14 and 15, the reactance of the capacitor 14 is reduced in magnitude at higher frequencies. This makes the phase angle g0 larger than 90, since it is known that 1 =2 are tan These conditions are illustrated in the vector diagram of FIG. 3, wherein the vector for the voltage U is inclined toward the positive feedback phase position due to the voltage drop U which has become smaller in relation to the voltage drop U Hence, the higher frequencies are amplified in addition.

If the frequency drops below the average frequency, the reactance of the capacitor 14 increases and thereby the voltage drop U increases. The result is, as illustrated in FIG. 4, that the phase angle (,0 becomes smaller than and the vector for the voltage U inclines toward the negative feedback phase position. Hence, the lower frequencies are considerably suppressed.

The magnitude of the positive and the negative feedback may be adjusted via the potentiometer 17. Care must be taken, however, that in connection with the positive feedback, and thereby also during the raising of the desired higher frequencies, a safe distance must be maintained from the self-excitation limit of the amplifier. Since the aforedescribed phase control connection 14, 15 does not depend upon the input amplitude of the amplifier, the magnitude of the positive and the negative feedback may be firmly established at the same time.

It is recognized that the raising of the amplitude of the high frequencies and the lowering of the amplitude of the low frequencies is easy to attain in a very simple manner by means of the aforedescribed phase control connection 14, 15, without having to use complicated bandpass filters. On the other hand, the aforedescribed phase control connection 14, 15 may also be varied. It is thus possible, for example, to substitute an inductive reactance or other suitable phase changing component for the reactive impedance 14. It would then be necessary merely to determine a correct phase position for the positive and negative feedback. Furthermore, the electrical center 13 between the impedances 14 and 15 may be connected to the amplifier stage 7 or the amplifier stage 9, in which case, also, the correct phase position must be determined by an appropriate selection of the transistors, such as by the selection of PNP transistors instead of NPN transistors. It is also possible to connect the point 13 to the input of a subsequent amplifier stage, in order to produce in this manner the positive and negative feedback. In FIGS. 1 and 6 the resistors 43 and 44 lead off the unused half-waves in order to prevent an undesirable shift in potential.

In the modification of FIG. 6, the collector resistor 91 of FIG. 1 is replaced by a primary winding 45 of a transformer 46. The transformer 46 has a secondary winding 47 having a center tap which is connected, for example, to the negative potential terminal 32. The series connection of the capacitor 14 and the resistor 15 is connected between the end terminals of the secondary winding 47 of the transformer 46. The emitter resistor 92 is shunted by a capacitor 48. In the modification of FIG. 6, also the series connection of the reactive impedance 14 and of the active impedance 15 is connected to two potentials whose respective polarity is in phase opposition relative to a predetermined reference potential, that is, the potential of the point 32. Regardless of the circuit differences between the embodiment of FIG. 1 and the modification of FIG. 6, the aforedescribed phase control connection 14, 15 considerably reduces the amplitudes of low frequencies produced by the photoelectric transducer 1 and considerably increases the amplitudes of high frequencies produced by said transducer. Thus, the voltages which charge the capacitor 22 are essentially comprised of high frequencies. As a result, the RC members which determine the stopping constant of the machine may cause further reduction in the stopping interval.

The third feature of the present invention for reducing the time constant is the dimensioning of at least the last amplifying stage 24 in a manner whereby even small voltage amplitudes lead to overloading. In the embodiment of FIG. 1, the transistor 9 is also considerably overloaded, in addition to the transistor 24, so that its amplitudes are considerably limited. As illustrated in FIG. 5, the unlimited half-waves of the control voltage of the transistor 24 are indicated as curves 33 and 34, which are equal to the voltage 38 of the capacitor 22, since the resistor 23 (FIG. 1) has a negligibly small resistance value.

In FIG. 5, the area 30 between the curves 33 and 34 should be filled in, at an unlimited amplitude, by an appropriately great capacitor charge. The curve 38 corresponds to the discharge curve of the capacitor 22 and is plotted for 1-=1. The curves 35 and 36 represent the amplitudes which are limited by the overload. Only the area 39 has to be balanced here. The curve 37 is also plotted for i=1 and corresponds to a discharge curve of approximately one seventh the time constant of the curve 38. The graphical presentations of FIG. illustrate very clearly that when the amplitude is limited by 20% the stopping interval or period and thereby the magnitude of the RC members may be reduced by one seventh. This amplitude limitation, due to overloading of the amplifier, may be provided by appropriately great amplification, as well as by an appropriate selection of the operating or supply voltage between the points or terminals 31 and 32 and by suitable resistance values of the resistor 23, 25, 91 and 92.

While the invention has been described by means of specific examples and in specific embodiments, I do not wish to be limited thereto, for obvious modifications will occur to those skilled in the art without departing from the spirit and scope of the invention.

I claim:

1. A textile machine control system, comprising a stop control member, transducer means for producing alternating voltages in response to changes of yarn travel conditions in the machine, frequency-responsive circuit means connected to said transducer means for raising the amplitudes of high frequencies and lowering the amplitudes of low frequencies, a capacitor, rectifier means connecting said capacitor to said circuit means for changing the charge of said capacitor in response to changes in frequency-responsive amplitude, and amplifier means connecting said capacitor to said stop control member, whereby said system is' controlled for rapid stopping performance in response to small voltage changes of said transducer.

2. A textile machine control system according to claim 1, comprising a switching amplifier network having several cascade-connected stages of which at least one constitutes said amplifier means, said rectifier means being a full-wave rectifier network and connected between said one stage and a preceding stage of said amplifier network.

3. A textile machine control system according to claim 2, one of said amplifier stages having two output points whose respective output potentials have a phase opposed to that of a given reference potential, and said frequencyresponsive circuit means comprising a series connection of a reactive impedance and an active impedance extending between said two points and having an electrical midpoint connected to the input of a preceding stage of said cascade network so as to form a positive feedback for high frequencies and a negative feedback for low frequencies.

4. A textile machine control system according to claim 3, said amplifier network comprising a transistor ampli fying in each of said cascade stages, said one stage forming the output stage of said network, said two output points being connected with the emitter and the collector respectively of the transistor in the next preceding stage of said network, said full-wave rectifier and capacitor means being series connected between said two output points.

References Cited UNITED STATES PATENTS 3,043,991 7/1962 Schneider et a1 3l7130 3,104,346 9/1963 Marshall 317 X 3,470,424 9/1969 Flesselles et a1. 317-130 LEE T. HIX, Primary Examiner US. Cl. X.R. 

